Yes, Workgroup is not the issue here.
Firstly, as far as Remote access from the Internet is concerned, you actually only need Port 443 forwarded to your Server (for https:// access) and optionally Port 80 (http:// access - albeit the Dashboard will complain that your router is not working if
not forwarded but you can still access it with https://). However, Remote Access is also not your problem as you have internal network issues (can't ping Client from Server).
What happens if you try pinging the Client from the Server using the Client IP address? Equally can you ping the Server with both name and IP address? In your router, does it show both Client and Server as DHCP connected clients? Try restarting firstly your
router and then Server if you have not already done so.
Phil P.S. If you find my comment helpful or if it answers your question, please mark it as such.
